Darrel Bain's books are usually very good. I'm reading Prion Promises now and it's hard to stop reading. (Available on Fictionwise.)

Surprisingly, I am also enjoying Rip Foster Rides the Gray Planet. A 1950's era sci-fi novel. Heinlein-eqsue story. I expected a cheezy space opera, but the story is much more interesting than I expected. I think this one came from Manybooks.